FIG. 1 depicts a schematic diagram of a portion of a typical wireless telecommunications system in the prior art, which system provides wireless telecommunications service to a number of wireless terminals (e.g., wireless terminals 101-1 through 101-3) that are situated within a geographic region. The heart of a typical wireless telecommunications system is Wireless Switching Center ("WSC") 120, which may also be known as a Mobile Switching Center ("MSC") or Mobile Telephone Switching Office ("MTSO"). Typically, Wireless Switching Center 120 is connected to a plurality of base stations (e.g., base stations 103-1 through 103-5) that are dispersed throughout the geographic area serviced by the system and to local and long-distance telephone and data networks (e.g., local-office 130, local-office 139 and toll-office 140). Wireless Switching Center 120 is responsible for, among other things, establishing and maintaining calls between wireless terminals and between a wireless terminal and a wireline terminal, which is connected to the system via the local and/or long-distance networks.
The geographic area serviced by a wireless telecommunications system is partitioned into a number of spatially distinct areas called "cells." As depicted in FIG. 1, each cell is schematically represented by a hexagon; in practice, however, each cell usually has an irregular shape that depends on the topography of the terrain serviced by the system. Typically, each cell contains a base station, which comprises the radios and antennas that the base station uses to communicate with the wireless terminals in that cell and also comprises the transmission equipment that the base station uses to communicate with Wireless Switching Center 120.
For example, when wireless terminal 101-1 desires to communicate with wireless terminal 101-2, wireless terminal 101-1 transmits the desired information to base station 103-1, which relays the information to Wireless Switching Center 120. Upon receipt of the information, and with the knowledge that it is intended for wireless terminal 101-2, Wireless Switching Center 120 then returns the information back to base station 103-1, which relays the information, via radio, to wireless terminal 101-2.
When base station 103-1 is capable of communicating with wireless terminals 101-1 and 101-2 using code-division multiple access ("CDMA") technology, FIG. 2 depicts a block diagram of the salient components that base station 103-1 uses to prepare the datastream of symbols for transmission on the forward channel in accordance with IS-95. Base station 103-1 typically comprises demultiplexor 201, a bank of c forward channel radios, 203-1 through 203-c, summer 205, amplifier 207 and transmit antenna 209, interconnected as shown.
A multiplexed datastream of symbols from wireless switching center 120, comprising up to c datastreams is received by demultiplexor 201, in well-known fashion, wherein each of the individual datastreams are intended for transmission over a unique forward channel to a wireless terminal. Demultiplexor 201 demultiplexes the c datastreams, in well-known fashion, and routes each individual datastream to one of c forward channel radios, 203-1 through 203-c. Each forward channel radio spreads the received datastream into a 1.25 wide MHz forward channel signal, in well-known fashion, and then modulates the spread datastream onto a carrier, also in well-known fashion. As is well-known in the prior art, each forward channel radio can modulate the spread datastream onto any one of the available carrier signals available for use by that base station. The output of each of the c forward channel radios, 203-1 through 203-c, is summed by summer 205, amplified by amplifier 207 and radiated by antenna 209, in well-known fashion.
FIG. 3 depicts a block diagram of a typical IS-95 compliant forward channel radio in the prior art. Forward channel radio 203-i typically comprises: convolutional encoder 301, symbol repeater 303, block interleaver 305, multiplier 307, long code generator 309, decimator 311, multiplier 315, and modulator 317, interconnected as shown.
One disadvantage with a IS-95 forward channel in the prior art is that it has a rather limited data rate capacity, and, therefore, the need exists for a CDMA forward channel that is capable of a greater data rate. As is well-known in the prior art, one technique for increasing the data rate of the CDMA forward channel is to widen its band to 5 MHz or 10 MHz or more.